The title page should look like this with only one date mentioned on the Published by line. Second impressions would have additional text on the page, referring to the later printing.

or if they'd normally reset the text between impressions (my impression was that they're only likely to do that between different editions)...i.e. still not entirely sure if there might be "corrected" hardcover copies out there. Probably not, though.

If this mistake has been spotted after the first impression then it is entirely likely that it would have been have been changed.

If you do not already own a copy then you really need to get J.R.R. Tolkien - A Descriptive Bibliography by Wayne G. Hammond and Douglas A. Anderson, for an insight into how Tolkien's books changed by impression